Moisture compensating system

ABSTRACT

A system for measuring the moisture entrained in a batch of aggregate material discharged from a storage hopper and for compensating for said moisutre in a batch mixing apparatus. The system includes a plurality of electrical probes arranged to project into a free-falling stream of aggregate material in a plurality of vertical portions of said stream, as said stream is discharged from the storage hopper. Electrical circuit means connected to said probes create an electrical signal proportional to the conductivity and hence the moisture content of each vertical portion of the aggregate stream. Signal accumulating means is also provided to accumulate and integrate said electrical signals during the time interval of aggregate material flow past said probes to provide a resultant electrical signal which is proportional to the total entrained moisture in the aggregate batch. Data recording means is also provided to provide indicia of said moisture content of said aggregate in response to said resultant signal.

nited States Patent 1191 MacKinney Dec. 11, 1973 MOISTURE COMPENSATINGSYSTEM Paul W. MacKinney, 1012 E. Geneva Rd., Wheaton, 111. 60187 221Filed: 0a. 18, 1971 211 Appl. No.: 190,363

Related U.S. Application Data [62] Division of Serv No. 834,036, June17, 1969, Pat. No.

[76] Inventor:

Primary ExaminerRobert W. Jenkins Att0rney Hume, Clement, Hume & Lee,Ltd,

[57] ABSTRACT A system for measuring the moisture entrained in a batchof aggregate material discharged from a storage hopper and forcompensating for said moisutre in a batch mixing apparatus. The systemincludes a plurality of electrical probes arranged to project into afreefalling stream of aggregate material in a plurality of verticalportions of said stream, as said stream is discharged from the storagehopper. Electrical circuit means connected to said probes create anelectrical signal proportional to the conductivity and hence themoisture content of each vertical portion of the aggregate stream.Signal accumulating means is also provided to accumulate and integratesaid electrical signals during the time interval of aggregate materialflow past said probes to provide a resultant electrical signal which isproportional to the total entrained moisture in the aggregate batch.Data recording means is also provided to provide indicia of saidmoisture content of said aggregate in response to said resultant signal.

3 Claims, 10 Drawing Figures MOISTURE COMPENSATING SYSTEM Thisapplication is a division of application Ser. No. 834,036, filed June17, 1969, now U.S. Pat. No. 3,631,337, issued Dec. 28, 1971.

BACKGROUND AND GENERAL DESCRIPTION This invention generally relates to amoisture control system and apparatus and more specifically relates to asystem and apparatus for sensing and totalizing the entrained moisturein aggregate materials such as sand, stone, and the like.

As fully discussed in my previous U.S. Pat. No. 3,1 17,640, the moistureentrained in aggregate materials creates a constant problem whensuch'materials have to be mixed with water, such as in the manufactureof concrete. If the entrained moisture is not properly measured andcompensated for in the concrete mixing process, for instance, theresulting concrete will have a poor consistency and a variable slump.

Field operations have indicated that the general concepts embodied inthe apparatus described and claimed in my previous patent are sound, andthat invention has proven to be a successful apparatus for compensatingfor entrained moisture. However, the commercial embodiment of theapparatus, as illustrated in the drawings of said patent, involved acombination of electromechanical and fluidic means for sensing theentrained moisture in an aggregate and adjusting the batching scales forthe aggregate and water proportionately to compensate for the entrainedmoisture. The commercial embodiment of such system was thereforedifficult to adapt for use with current electronic weighing and batchingsystems. My field experience thus has indicated the need for an improvedapparatus incorporating the general concepts of the apparatus describedand claimed in my previous patent, which would create an electronicsignal accurately reflecting the total entrained moisture in anaggregate batch and which could be converted to a proportionateelectronic value for use in the measuring and weighing circuitry ofelectronic batch weighing systems.

Numerous devices have been devised in the past in an effort to senseentrained moisture in aggregate materials and the like electronicallyand to convert that sensed data into a proportionate electronic valuewhich could be fed into the circuitry of an electronic batching system.One such prior device is described in United States Pat. No. 3,252,530,issued to A. G. Bale, Jr., on May 24, 1966, wherein a single electrodeunit is placed in the discharge chute of an aggregate hopper to createan electrical signal which is proportional to the surface moisture ofthe aggregate in the hopper. Another prior device is illustrated in U.S.Pat. No. 2,750,144, issued to R. C. Beckwith, on June 12, 1956, whereina neutron source and detector are provided in the discharge throat of anaggregate hopper to create the electronic signal proportional to themoisture sensed in the aggregate.

These devices such as illustrated in the Bale and the Beckwith patentsprovide only partial solutions to the problems presented by electronicbatch measuring and weighing, because such devices fail to accuratelymeasure the total moisture entrained in an aggregate batch. Since theseprior systems rely upon a single moisture reading, taken at an arbitrarytime during the batching process, the systems have the inherentdisadvantage of locking into the weighing circuitry an electronic signalwhich is not proportionate to the moisture entrained in the batch.Substantial errors result from the inability of these systems to accountfor the variations in moisture content of the aggregate batch caused byrandom distribution of water in the aggregate, both vertical andhorizontal stratification of the entrained moisture and variations inthe aggregate compaction. In practice, a single moisture reading takenin one location of an aggregate batch has not been found to produce asignal accurately representative of the moisture in the entire batch.

Accordingly, I have invented the system and apparatus which eliminatesthe foregoing problems presented by'previous devices. This presentinvention also is an improvement in the system disclosed in mypreviously issued patent whichpermits the moisture sensing signals to bereadily adaptable for use in an electronic weighing and batching system.

To avoid the inaccuracies presented by a single reading of the entrainedmoisture in an aggregate batch, the system in accordance with thepresent invention relies upon a plurality of moisture readings which aretaken continuously as the batch is dispensed from the storage hopperinto the weighing or mixing hopper. Moreover, the present systemutilizes moisture readings from a plurality of locations in thefree-falling stream of aggregate. Thus, unlike prior attempts toaccurately sense the moisture in aggregates, the present system willproduce a moisture reading which is unaffected by the compaction,stratification or gradation of the aggregate material.

Furthermore, in accordance with this invention, the plurality ofmoisture readings are taken from a plurality of locations throughout theentire time during which the batch is being dispensed, and then areelectronically integrated and totalized. As a result, the totalizedelectronic value of the moisture signal is an accurate representation ofthe total moisture content of the aggregate batch. The accurateelectronic signal hence can be utilized to adjust the weight ofaggregate material and the weight or volume of water which are mixed, tothereby compensate for the total entrained water in the aggregate batch.

In one form of the system, the signal, which is proportionate tothe'total moisture content of the aggregate batch, is used to operatevisual or audible indicia which permits manual adjustment of thebatching system to compensate for the entrained water. In anotherembodiment, the signal is converted into impulses, by the appropriatecircuitry, so as to automatically adjust the water added to the mixtureby sending appropriate compensating signals to an impulse-counting watermeter. Finally, in a third embodiment the electronic signal is connectedthrough appropriate circuitry to the electronic aggregate and waterweighing and dispensing circuits of an electronic batching system toautomatically compensate for the entrained moisture in the aggregate byincreasing the aggregate and decreasing the water mixed in the batchingprocess.

Further objects, features, and advantages of the present moisturecompensating system will become apparent from the following descriptionof several embodiments thereof, taken in conjunction with the drawings,in which:

FIG. 1 is an elevational view, in partial section, illustrating thelocation of the moisture-sensing electrodes of the present systemadjacent the discharge chute of an aggregate batching hopper;

FIG. 2 is a plan view of the electrodes, as viewed along the line 22 inFIG. 1, illustrating the location of the electrodes with respect to thehopper discharge chute, and schematically illustrating a series circuitconnection for the electrodes;

FIG. 3 is a view of the electrodes corresponding to FIG. 2, andillustrating a parallel circuit connection for the electrodes;

FIG. 4 is a schematic illustration of one form of data recording devicewhich can be incorporated in the system of this invention to registerthe amount of entrained moisture sensed by the electrodes illustrated inFIGS. l-3;

FIG. 5 is a side view, in partial section, of the data recording deviceillustrated in FIG. 4;

FIG. 6 is a schematic illustration of a second form of data recordingdevice for receiving the electronic signals from the electrodesillustrated in FIGS. 1-3 and converting the signals into a train ofimpulses representative of the entrained moisture measured by theelectrodes;

FIG. 7 is a schematic illustration of a suitable circuit for utilizingthe second form of data recorder, as illustrated in FIG. 6, to convertthe electrode signals into an impulse train which automatically adjustsa pre-set impulse water meter to thereby compensate for the entrainedmoisture sensed by the electrodes;

FIG. 8 is a schematic illustration of a third form of data recordingdevice which can be incorporated in the system of this invention, andwhich is adapted to automatically adjust the pre-set aggregate and waterscales ofa conventional electronic batch weighing and mixing system tocompensate for the entrained moisture.

FIG. 9A is a schematic illustration of a suitable circuit for adjustingthe aggregate scale employed with the form of data recording deviceillustrated in FIG. 8; and

FIG. 9B is a schematic illustration ofa suitable circuit for adjustingthe water scale employed with the data recording system of FIG. 8.

EXEMPLARY EMBODIMENTS Referring initially to FIG. 1 of the drawings, thesystem in accordance with this invention is designed for use with aweighing and batching system which includes an aggregate storage hopper10, a suitable weighing hopper 20, and a water supply 30. As wellknownby those skilled in the art, aggregate material, such as sand or stoneor the like, is stored in the hopper l0 and is selectively dispensedinto the weighing hopper 20. From the weighing hopper 20, the materialmay be charged into a suitable mixer (not shown) where the material maybe mixed with other aggregates and with water from the supply 30.

The storage hopper 10 includes a conventional discharge chute l2, havinga selected cross-sectional area, through which the aggregate stored inthe hopper 10 can be discharged. Swinging gates 14 extend across thelower end of the chute 12 and can be operated to selectively dispensethe desired amount of aggregate through the chute at a constant rate offlow. These gates 14 can be automated by suitable control devices (notshown) so that the gates will dispense a selected weight or volume ofaggregate from the storage hopper 10 into the weighing hopper 20. Ofcourse, the moisture compensating system in accordance with thisinvention can be used with other suitable dispensing and weighingapparatus, and can be used in systems for mixing aggregates for end usesother than concrete without departing from the spirit or scope of thisinvention.

In accordance with this invention, a plurality of electronic probes 40,42 is placed directly below the throat 12 of the storage hopper 10, in aposition which assures that the probes will extend into the stream ofthe freefalling aggregate when the hopper gates 14 are opened. Asindicated in FIG. 1, these probes 40, 42 are supported in a decliningposition in the path of the discharged aggregate by being pivotallyconnected, by a pivot pin 16 or the like, to a suitable supportingstructure 18. The pivoted mounting and the declining position of theprobes 40, 42 will allow the probes to deflect out of the aggregate pathwhen a foreign object or compacted mass of aggregate is discharged fromthe hopper 10. Without such pivoted arrangement, the foreign object orcompacted aggregate would restrict the flow of aggregate past the probesand would possibly shortcircuit the probes and thereby result in a falsemoisture signal for the batch. Counter-weights 22 and associatedsupporting chains 23 balance the probes 40 so that the probes willcontinue to project into the free-falling aggregate stream under normalconditions.

Furthermore, a flexible skirt 24, made from a suitable wear-resistantelastomeric material, is mounted to the support structure 18 directlyabove the probes 40. This skirt 24 includes a central aperture 25, whichis preferably square, through which the aggregate stream will flow. Theskirt 24 thereby confines the free-falling aggregate stream and protectsthe probes and the adjacent portions of the structure 18 from beingdamaged, or from accumulating an excessive amount of aggregate.

As clearly indicated in FIGS. 2 and 3, the system in accordance withthis invention preferably includes four probes 40a-d arranged on aninsulating support plate 41 along one side of the hopper chute 12, andfour probes 42a-d arranged on a similar insulating plate 43 along theother side of the hopper chute. The probes are arranged on theinsulating plates 41 and 43 so that a pair of closely spaced probes(e.g., 40a and 40b; 40c and'40d; 42a and 42b; and 420 and 42d) projectinto each quadrant of the free-falling aggregate stream. By thisarrangement, a measurable electrical current can flow through theportion of the aggregate stream flowing between the adjacent probes(e.g., 40a and 40b) to complete an electrical circuit. The probes 40 and42 are spaced laterally a sufficient distance so that there will be noopportunity for a short circuit to occur across the aligned probes, suchas between the probes 40a and 42a.

The electrical conductivity of the aggregate stream will be directlyrelated to the amount of moisture entrained in the aggregate. Hence, thecurrent which will flow through the aggregate stream between theadjacent pairs of electrodes (e.g., 40a and b) is directly proportionalto the moisture entrained in the flowing aggregate, so that the systemof this invention will create a measurable electronic signal which isproportional to the moisture entrained in each quadrant of the flowingaggregate stream. Such signals are thereby unaffected by any verticalstratification of the moisture in the aggregate batch.

From the above description, it is also apparent that horizontalstratification of the moisture in a batch of aggregate can be accountedfor in this system by taking moisture readings from each quadrant of theflowing aggregate stream continuously as the aggregate flows past theprobes 40, 42. The resulting plurality of electrical signals then can beintegrated and totalized to provide a final output signal which isdirectly proportional to and an accurate representation of the totalenrained moisture content of the entire batch of aggregate.

Thus, this resulting output signal can be utilized to create a visual oraudible signal of the entrained water content of the batch, so thatmanual adjustment of the water and aggregate of a mixture can be made.Alternatively, the output signal of this system can be employed tocreate an input signal for electronic weighing and batching circuitrywhich allows an electronic batching system to automatically compensatefor the entrained moisture in the aggregate.

FIGS. 2 and 3 illustrate two acceptable means of electrically connectingthe above described probes 40, 42 to pick up the measurable variationsin current which will flow through the aggregate stream during abatching operation.

FIG. 2 illustrates a circuit 46 for connecting the probes in series sothat the current is directed through the aggregate stream in all fourquadrants, across the gap between the pairs of closely spaced probes(e.g., 40a and 40b). The total output signal of the circuit 46,registered at the output leads 47, therefore will be proportional to theconductivity, and thus to the moisture content of the aggregate flowingthrough the four quadrants. FIG. 3 illustrates a circuit 48 whichconnects the probes so that the pairs of closely spaced probes (such as40a and b and 400 and d) are in parallel. This parallel circuitconnection likewise produces an output signal at the output leads 49which is proportional to the conductivity of the aggregate flowingthrough the four quadrants. Either the series circuit 46 or the parallelcircuit 48 can be employed in the system of this invention; The choiceof circuits will depend upon the field conditions, such as thecompaction of the aggregate, prevailing at the particular installation.

As also indicated in FIGS. 2 and 3, the output leads 47 or 49 for theprobe circuit are connected to a variable speed motor 50 through asuitable motor control unit 60. The motor 50 preferably comprises adirect current servo motor which has a wide speed range and which willquickly respond to the variations in a reference voltage to vary themotor output speed proportionately. In addition, the motor control unitincludes suitable transformer and amplifier components to convert thevarying voltage signal occurring across the probe circuit leads 47 or 49into a proportionately varying reference voltage for the motor 50. Thecontrol 60 is designed to start the operation of the motor 50 when theprobe circuit is completed by the initial flow of aggregate past theprobes 40 and 42 and to stop the motor 50 when the flow of the aggregateends. The control 60 also functions to totalize and time-integrate thesignals at the probe leads 47 or 49 so that the total output revolutionsfor the shaft 51 of the motor 50 is proportional to the total moistureof the aggregate batch, as measured by the probes 40 and 42. Suitablemotors and control units for performing the above functions arepresently available from Electro-Craft Corporation, 1,600 Second Street,Hopkins, Minnesota, under the Electro-Craft Stock Nos. EISOMG and E150M,respectively.

Therefore, in accordance with this invention, the total outputrevolutions of the motor shaft 51 is a direct function of the time spanthrough which the aggregate flows past the probes 40, 42, and thusproportional to the size of the aggregate batch. Moreover, the speed ofthe motor shaft 51 will be varied during the flow of the aggregate, bythe varying signal produced at the probe output leads 47 or 49.Accordingly, the total output revolutions of the shaft 51 will beproportional to the moisture content of the aggregate, as well as to thetotal size of the aggregate batch. The motor shaft 51 can thereby beutilized to indicate the total entrained moisture in the batch ofaggregate dispensed from the hopper 10.

FIGS. 4 and 5 illustrate one form of data recording device which can becoupled to the motor 50 to indicate the total entrained moisture sensedby the above described system. In this device 70, the motor 50 iscoupled to a gear train 72 which reduces the output of the motor shaft51. In the preferred arrangement, the gear train 70 is selected so thatan output shaft 73 of the gear train will revolve less than one completerevolution, even for the largest anticipated aggregate batch. With thisarrangement, an indicator arm 74 can be mounted on the gear train shaft73, and a numerical dial face 75 can be provided on the device 70. It isapparent that the rotation of the arm 74 will represent theproportionate rotation of the motor shaft 51, and will thereforerepresent the total amount of entrained moisture cumulatively measuredby the probes 40, 42 and the associated circuitry. The device 70 hencecan be calibrated to provide a visual reading of the total mois turecontent of a batch of aggregate.

The device 70 also includes a suitable reset circuit (not shown) toreset the arm 74 and the motor 50 back to their zero positions aftereach aggregate batch. Further, the device 70 includes conventionalmanual speed adjustment controls 71, zero and span adjustment controls76 and 77, and a control switch 78. If desired, a RPM counter 79 can beincorporated in the device to provide a visual reading of the actualspeed of the motor shaft 51.

When calibrating the device 70, the zero and span controls 76 and 77 areadjusted to the desired settings to meet the particular fieldconditions. Then, when using the device 70, the operator of theaggregate weighing and batching system would operate suitable controls(not shown) to open the gates 14 and start the discharge of the batch ofaggregate from the hopper 10. The flow of the batch of aggregate pastthe probes 40, 42 will then cause the motor shaft 51 and the indicatorarm 74 to rotate in proportion to the moisture in the aggregate. The arm74 and dial 75 will thereby provide visual reading of the entrainedmoisture, and the operator can adjustthe size of the aggregate and waterto be mixed to compensate for this measured moisture.

FIG. 6 illustrates a second form of data recording device 80 which canbe utilized with the present moisture compensating system, and which isparticularly suited for use with a batching system which includesimpulsecounting type water meters. To create the electrical impulses foruse in such a system, the device 80 includes a gear head 82 mounted onthe motor shaft 51, and a leaf spring switch 84 positioned adjacent thegear head.

The gear head 82 has a selected number of teeth 83 which will engagewith the contact arms 84a of the switch 84 as the motor shaft 51revolves. By this arrangement, the motion of each tooth 83 will closethe switch 84, and each partial revolution of the gear 82 will produce aknown train of electrical impulses. The impulse output of the switch 84is thus directly proportional to the revolutions of the motor 50 and tothe total entrained aggregate moisture sensed by the probes 40 and 42.This impulse output of switch 84 hence can be used to energize animpulse actuating circuit 85 (FIG. 7) including suitable solenoiddevices. The circuit 85 in turn can be arranged to energize a digitaldisplay counter and totalizer 86 which is calibrated to indicate thetotal gallons or pounds of aggregate moisture sensed by the probes. Thebatching system operator then can use this data to adjust the size ofthe aggregate batch.

The impulse output of the switch 84 also can be utilized toautomatically adjust an impulse counting water meter to decrease thesize of the water batch from a pre-set value to a value whichcompensates for the entrained moisture in the aggregate. As indicated inFIG. 7, a suitable circuit for accomplishing this water meter adjustmentincludes an impulse water meter 90 which is coupled to the impulseactuating circuit 85 and the impulse totalizer 86. As well-known tothose skilled in the art, the impulse water meter 90 is designed tocontrol the operation of a water valve, such as the valve 91 illustratedin FIG. 1, in response to an impulse signal, so that a given number ofimpulses received by the meter results in the discharge of a selectedquantity of water through the valve and into the batch mixing apparatus.Suitable control means, such as the span and zero adjustment referred towith respect to the data recorder 70, also can be included on the device80.

The circuit for the impulse water meter 90 also includes a pre-setswitch 92 through which a set signal can be fed into the circuit. Themagnitude of the preset signal is chosen by the batch system operator tosend a selected number of impulses to the meter 90, and therebydischarge a proportional amount of water through the meter. Inaccordance with this invention, this circuit also includes a suitablesubtracter circuit 94 which is adapted to receive the impulses createdby the circuit 85 and subtract those impulses from the impulses fed intothe circuit by the pre-set switch 92. Finally, the circuit includes aninhibitor gate 96 and a time delay switch 98. The inhibitor gate 96inhibits the conduction of any impulses to the impulse water meter 90until after the subtracter circuit 94 has functioned to subtract theimpulses emitted by the actuating circuit 85 from the impulses fed intothe circuit by the pre-set switch unit 92. In turn, the time delay gate98 functions to delay the removal of the inhibit signal from theinhibitor gate 96 until after the total aggregate batch has beendispensed from the hopper l0, and the impulse actuating circuit 85 hastransmitted corresponding impulses to the subtracter circuit 94. In thismanner, the circuit illustrated in FIG. 7 assures that the impulsescreated by the actuating circuit 85, which are indicative of the totalmoisture content in the aggregate sensed by the probes 40 and 42, aresubtracted from the pre-set impulses from the switch unit 92 before anyimpulses are sent to the meter 90, and there is no danger that theimpulses from these two sources would meet at the meter and cancel eachother out.

FIGS. 8 and 9 illustrate a third form of device 100 in accordance withthis invention. The device 100 is adapted to be tied-in to an electronicweighing and batching apparatus to automatically compensate for theentrained moisture of an aggregate by increasing the setting of anaggregate scale and decreasing the setting ofa water scale in proportionto the total entrained aggregate moisture.

Accordingly, the device 100 includes the motor 50 which, as describedabove has an output directly proportional to the total entrainedaggregate moisture accumulated and measured by the probes 40, 42. A gearreducer 101 is provided on the output end of the motor 50 to gear themotor output down so that the associated output shaft 102 will notrotate a complete revolution for the biggest anticipated batch ofaggregate. This arrangement allows the connection of an indicator arm103 to the other end of the shaft 102 so as to provide a visual readingof the measured moisture content on a suitable dial face 104.

In accordance with this invention, a driving gear 106 is mounted on themotor output shaft 102 and a pair of pinions 108 and 110 are mounted inmeshing engagement with the gear 106 so that the pinions rotate inopposite directions. The gear 106 and pinions 108 and 1 10 will therebyrotate in proportion to the output rotation of the motor 50. Further, apotentiometer 112 is directly joined to the pinion I08, and a similarpotentiometer 114 is directly joined to the pinion 110. By thisarrangement the operation of the motor 50 will change the settings ofthe potentiometers 112 and 114 in opposite directions, and the change inthe resistance provided by each potentiometer in turn will beproportional to the total entrained moisture signal which actuated themotor.

Further, in accordance with this invention, the potentiometers 112 and114 of the device 100 are connected into the circuitry of an electronicbatching system to automatically compensate for the entrained moisturein the aggregate. FIG. 9A illustrates a suitable circuit forautomatically adjusting theaggregate in such a manner, and FIG. 9Billustrates a suitable circuit for adjusting the water.

As illustrated in FIG. 9A, a conventional electronic batching systemincludes a potentiometer control for selecting the desired weight ofaggregate to be included in a batch. Generally, the potentiometer 120 isset by an operator so that it feeds a predetermined resistance intoconventional aggregate scale circuitry 121 which represents the desiredweight of aggregate. When this desired weight is measured by theaggregate scale, the potentiometer 120 triggers a signal which stops theflow of aggregate onto the scale.

Under ideal conditions, where the aggregate has no entrained water, theaggregate weighed out by the scale circuit 121 will be accurate, and theamount of aggregate included in the batch will be equal to the valuepre-set in the aggregate potentiometer 120. However, under mostpractical conditions, the aggregate weight will include the weight ofentrained water and, hence, an additional amount of aggregate must beweighed to compensate for that water. To accomplish this, thepotentiometer 112 of the device 100 is connected in series with theaggregate potentiometer 120, so that the resistances of the twopotentiometers are added. Since the setting of the potentiometer 112 isa function of the entrained moisture content of the aggregate, as aresult of the operator of the motor 50, the potentiometer 112 adds aresistance to the potentiometer 120 which is proportional to theentrained aggregate moisture. The aggregate scale circuitry 121 isthereby adjusted to add more aggregate weight to the batch to compensatefor the entrained moisture.

As illustrated in H6. 98, a conventional electronic batching systemincludes corresponding water scale circuitry 131 which responds to thesetting of a control potentiometer 130 to add a selected weight of waterto the aggregate batch. In accordance with this invention, thepotentiometer 114 of the device 100 is electrically coupled with thepotentiometer 130 to decrease the pre-set valve in the potentiometer 130and thereby compensate for the entrained aggregate moisture.

Since the operation of the motor 50 in the device 100 rotates thepotentiometer 114 in the opposite direction with respect to theabove-described potentiometer 112, this subtraction of electrical valuescan be accomplished by coupling the potentiometers 114 and 130 as shownin FIG. 93, so that the resistance of the potentiometer 114 issubtracted from the pre-set resistance of the potentiometer 130. Thus,the water scale circuit will receive an actuating signal which has beenreduced in proportion to the measured aggregate moisture, and the amountof water added to the batch of aggregate will be correspondinglyreduced.

Although the invention has been described with a certain degree ofparticularity, it should be understood that the present disclosure hasbeen made only by way of example. Consequently, numerous changes in thedetails of construction and the combination and arrangement ofcomponents as well as the possible modes of utilization, will beapparent to those familiar with the art, and may be resorted to withoutdeparting from the spirit and scope of the invention as claimed.

What is claimed is: l

1. In an aggregate batching and mixing'apparatus including an impulseconnecting water meter device for adding water to a batch of aggregatein response to impulses received by said meter, the improvementcomprising a system for measuringthe moisture entrained in a batch ofaggregate material discharged from a storage hopper for mixture withwater from said meter to permit compensation for said entrainedaggregate moisture, said system comprising: j

a plurality of electrical probes arranged in an array which projectssaid probes into a plurality of portions of an aggregate streamdischarging from said hopper;

electrical circuit means connected to said probes and creating anelectrical signal proportional to the conductivity and hence theentrained moisture content of the stream of aggregate flowing past saidprobes in each of said portions of said stream; variable speedelectrical motor connected to said circuit means and adapted to produceoutput revolutions of a motor output shaft proportional to the timeinterval of flow of aggregate past said probes and further proportionalto the variations in electrical conductivity of said flowing aggregatestream as sensed by said probes, so that the revolution of said motorshaft is thereby proportional to the size of said aggregate batch and tothe total entrained moisture in said aggregate batch; means connected tosaid motor output shaft to create a first train of electrical impulsesproportional to the revolution of said shaft and thus proportional tothe measured entrained moisture in said aggregate batch;

electrical circuit means for creating a second train of pre-setelectrical impulses for actuating said water meter to dispense aselected quantity of water into said batching apparatus;

electrical circuit means for subtracting said first train of electricalimpulses from said second pre-set train of impulses to provide a finalimpulse train which compensates for the measured entrained moisture insaid aggregate batch; and

electrical inhibitor means for inhibiting the receipt of electricalimpulses by said water meter until said subtracter circuit functions toprovide said final impulse train;

whereby said system provides an impulse signal to said water meter whichcompensates for the measured entrained moisture in said aggregate batch.

2. A moisture compensating system in accordance with claim 1 whereinsaid system includes a digital counter actuated by said first train ofimpulses to provide a digital display of said measured entrainedaggregate moisture.

3. In an electronic aggregate batching and mixing apparatus including anelectrical water scale potentiometer for creating a final electricalsignal representative of a selected quantity of water and an electricalaggregate scale potentiometer for creating a final electrical signalrepresentative of a selected quantity of aggregate, the improvementcomprising a system for measuring the moisture entrained in a batch ofaggregate material discharged from a storage hopper for mixture with aquantity of water and for automatically compensating for said entrainedaggregate moisture, said system comprising:

a plurality of electrical probes arranged in an array which projectssaid probes into a plurality of portions of an aggregate streamdischarging from said hopper;

electrical-circuit means connected to said probes and creating anelectrical signal proportional to the conductivity and hence theentrained moisture content of the stream of aggregate flowing past saidprobes in each of said portions of said stream; a variable speedelectrical motor connected to said circuit means and adapted to produceoutput revolutions of a motor output shaft proportional to the timeinterval of flow of aggregate past said probes and further proportionalto the variations in electrical conductivity of said flowing aggregatestream as sensed by said probes, so that the revolution of said motorshaft is thereby proportional to the size of said aggregate batch and tothe total entrained moisture in said aggregate batch;

electrical potentiometer means joined to said motor output shaft andadapted to create first and second electrical signals which areproportional to the output of said motor shaft and hence to the measuredentrained aggregate moisture;

electrical circuit means connecting said first electrical signal to saidaggregate scale potentiometer to increase the value of the finalelectrical signal emitted from said aggregate scale potentiometer tocompensate for the measured entrained aggregate moisture byproportionately increasing the quantity of aggregate for a batchmixture; and

compensate for the measured entrained aggregate moisture byproportionately decreasing the quantity of water for a batch mixture.

1. In an aggregate batching and mixing apparatus including an impulseconnecting water meter device for adding water to a batch of aggregatein response to impulses received by said meter, the improvementcomprising a system for measuring the moisture entrained in a batch ofaggregate material discharged from a storage hopper for mixture withwater from said meter to permit compensation for said entrainedaggregate moisture, said system comprising: a plurality of electricalprobes arranged in an array which projects said probes into a pluralityof portions of an aggregate stream discharging from said hopper;electrical circuit means connected tO said probes and creating anelectrical signal proportional to the conductivity and hence theentrained moisture content of the stream of aggregate flowing past saidprobes in each of said portions of said stream; a variable speedelectrical motor connected to said circuit means and adapted to produceoutput revolutions of a motor output shaft proportional to the timeinterval of flow of aggregate past said probes and further proportionalto the variations in electrical conductivity of said flowing aggregatestream as sensed by said probes, so that the revolution of said motorshaft is thereby proportional to the size of said aggregate batch and tothe total entrained moisture in said aggregate batch; means connected tosaid motor output shaft to create a first train of electrical impulsesproportional to the revolution of said shaft and thus proportional tothe measured entrained moisture in said aggregate batch; electricalcircuit means for creating a second train of pre-set electrical impulsesfor actuating said water meter to dispense a selected quantity of waterinto said batching apparatus; electrical circuit means for subtractingsaid first train of electrical impulses from said second pre-set trainof impulses to provide a final impulse train which compensates for themeasured entrained moisture in said aggregate batch; and electricalinhibitor means for inhibiting the receipt of electrical impulses bysaid water meter until said subtracter circuit functions to provide saidfinal impulse train; whereby said system provides an impulse signal tosaid water meter which compensates for the measured entrained moisturein said aggregate batch.
 2. A moisture compensating system in accordancewith claim 1 wherein said system includes a digital counter actuated bysaid first train of impulses to provide a digital display of saidmeasured entrained aggregate moisture.
 3. In an electronic aggregatebatching and mixing apparatus including an electrical water scalepotentiometer for creating a final electrical signal representative of aselected quantity of water and an electrical aggregate scalepotentiometer for creating a final electrical signal representative of aselected quantity of aggregate, the improvement comprising a system formeasuring the moisture entrained in a batch of aggregate materialdischarged from a storage hopper for mixture with a quantity of waterand for automatically compensating for said entrained aggregatemoisture, said system comprising: a plurality of electrical probesarranged in an array which projects said probes into a plurality ofportions of an aggregate stream discharging from said hopper; electricalcircuit means connected to said probes and creating an electrical signalproportional to the conductivity and hence the entrained moisturecontent of the stream of aggregate flowing past said probes in each ofsaid portions of said stream; a variable speed electrical motorconnected to said circuit means and adapted to produce outputrevolutions of a motor output shaft proportional to the time interval offlow of aggregate past said probes and further proportional to thevariations in electrical conductivity of said flowing aggregate streamas sensed by said probes, so that the revolution of said motor shaft isthereby proportional to the size of said aggregate batch and to thetotal entrained moisture in said aggregate batch; electricalpotentiometer means joined to said motor output shaft and adapted tocreate first and second electrical signals which are proportional to theoutput of said motor shaft and hence to the measured entrained aggregatemoisture; electrical circuit means connecting said first electricalsignal to said aggregate scale potentiometer to increase the value ofthe final electrical signal emitted from said aggregate scalepotentiometer to compensate for the measured entrained aggregatemoisture by proportionately increasing the quantity of aggregate for abatch Mixture; and electrical circuit means connecting said secondelectrical signal to said water scale potentiometer to decrease thevalue of the final electrical signal emitted from said water scalepotentiometer to compensate for the measured entrained aggregatemoisture by proportionately decreasing the quantity of water for a batchmixture.